R-1830 vs. Allison V-1710

It's 1938 and the war department has told you you have to pick one of their two 1000 horsepower class babies for further development as fighter engines at the expense of dropping the other. This move would force the Army and Navy to settle on either an inline or a radial for planes in that size category. What would you pick?

Two different engines, two different functions - actually it would be the war department telling you what engine to put into your aircraft based on your design.

Click to expand...

right, the premise is that the war department has decided to tell everyone to use the same engine and they are letting you (personally) as the "engine czar" decide what engines everyone is going to build.

For fighters I am not at all sure that I would go R-1830 as long as I was sure that Allison would be successful in developing the better supercharger and WI models.

The question is for me (at least for USAAF and lend lease) what do I want. Cleaner a/c with better long range potential (P-39, P-63, P-40, P-38, P-51) or the immediate gratification of 1830 going to R-2800 in development and bringing the P-47, F6F and P-47 into the field.

Interesting debate.

If In Line was 'selected' in 1938, then the P-39 may have had a better life, similar to P-63 and the engine capability for a 1942 Mustang may have been accelerated by a 1939 requirement to develop a supercharger faster.

R-1830 passed its 150-hr test at 1,000hp in 1936, the V-1710 followed in 1937.

The thing with the R-1830 is that design work on the R-2800 was concurrent in the same year. The V-1710 was still stuck with its standardised power section, turbochargers were all well and good in the lengthy booms of the P-38 but not practicable (with the then-current technology) for P-39-sized fighters.

The supercharged -143/145 versions of the Allison would not see light of day until the end of the war.

If the P-40 were never developed as an Allison engined plane and was instead a better P-36 with armor, self sealing tanks, realistic armament and two-stage supercharging, how would that have affected early AAF operations?

Similar, what if the P-51 was built to fly with Packard Merlins from day one?

Choosing between the P&W and the Allison gives Wright a rather unfair advantage doesn't it?

Allison powered B-24s?

Allison powerd C-47s

Allison powered Catalina's

OK, I know you said fighter engine but there was no way that the P&W R-1830 wasn't going to stay in contention in that catagory, With the basic engine in production for so many other aircraft there was no chance of it being dropped.

That being said the Allison had more potential. Liquid cooled V-12 engines were heavier for their displacement but could achive more HP per cubic inch. The question starts to become which engine could give the most HP per pound and/or per sq ft of frontal area. the close cowled BMW style of installation still being a few years off.

In 1938 the choice is between the R-1830 which was a proven engine that was in production but perhaps lacking in development potential and the V-1710 with more potential but was, despite passing a type test, a tool room produced experamental engine.

Maybe P&W did need more money and engineering staff but they were one of the 2 largest engine makers in the US at the time. Production engines were the Wasp Jr., the Wasp, the Hornet, the Twin Wasp Junior, and the Twin Wasp. For a brief period of time they tried to market the Twin Hornet and were working behind the scenes on the R-2000, the R-2800 and several liquid cooled projects. And they still had trouble with the 2 stage supercharger on the R-1830. An extra 10% of displacement probably wouldn't have turned things around much going for the R-2000. Plwase remember that 14 R-2800 sized cylinders work out to 2180 cu in and also that the later high powered R-2800s had little more in commen with the 2000hp versions than the bore and stroke. Forged heads instead of cast, cylinder barrels with Aluminum fin muffs on them instead of machined steel fins, different crankcases, crankshafts, pistons and so on. Without a total redsign of the R-1830 (and different manufacturing techniques) the R-1830 was not going to reach the output of the later R-2800s per cubic inch.

If the P-40 were never developed as an Allison engined plane and was instead a better P-36 with armor, self sealing tanks, realistic armament and two-stage supercharging, how would that have affected early AAF operations?

Similar, what if the P-51 was built to fly with Packard Merlins from day one?

Click to expand...

Haven't we been over this before?

While you can cetainly put a P-40E style wing on a P-36 style fuselage and put in armour and self sealing tanks, the two stage supercharged R-1830 might have been just a bit harder. The weight might not have been a big problem but the volume needed by the intercooler might have been just little more difficult.

THe demonstrated performance of the R-1830 engine, while better than the Allison engines, wasn't so dramaticly better that the draggier radial engine vesion would have turned into a super fighter. the Two stage engine offered 1000hp at 19,000ft at "military rating". If somebody has any better information please let me know.

The P&W sytem of two stage superchargering was different than the Merlins. The P&W system used an engine driven supercharger with one gear ratio. the auxilary stage was not driven at sea level or for takeoff so the engine operated as a single stage engine until the hight of about 8-9,000 ft was reached at which point the auxilary supercharger was clutched in. This boosted the poer but as the plane climbd the power fell off untill the plane reached aboiut 16,000-17,000 at which point the auxilary supercharger shifted to high gear and power peaked at 19,000ft. The intercooler was between the auxialry stage and the engine supercharger and so did nothing to cool the intake charge after it left the engine supercharger, The intercooler was an air to air unit but I have no idea how good it was.
Note that as far as I can tell this is just about the same system used on the R-2800s in the F4U, the Hellcat and the P-61 A B models.

If the P-51 had flown as a Merlin powered plane from the start it would have first shown up in the Summer of 1942 ( using the 2 speed but not 2 stage engines from the P-40F) which would mean well over 600 Allison engined versions not being produced and probably a several month delay in getting the production ramped up for the Merlin version. P-51B is still going to have to wait for the 2 stage Merlin to be developed and put into mass production.
It might have ment no Mustang at all. With no Merlins ( of any supercharger type ) available from US sources in 1940 the British might never have signed the contract to develop the Mustang.

Choosing between the P&W and the Allison gives Wright a rather unfair advantage doesn't it?

Allison powered B-24s?

Allison powerd C-47s

Allison powered Catalina's

OK, I know you said fighter engine but there was no way that the P&W R-1830 wasn't going to stay in contention in that catagory, With the basic engine in production for so many other aircraft there was no chance of it being dropped.

That being said the Allison had more potential. Liquid cooled V-12 engines were heavier for their displacement but could achive more HP per cubic inch. The question starts to become which engine could give the most HP per pound and/or per sq ft of frontal area. the close cowled BMW style of installation still being a few years off.

In 1938 the choice is between the R-1830 which was a proven engine that was in production but perhaps lacking in development potential and the V-1710 with more potential but was, despite passing a type test, a tool room produced experamental engine.

Maybe P&W did need more money and engineering staff but they were one of the 2 largest engine makers in the US at the time. Production engines were the Wasp Jr., the Wasp, the Hornet, the Twin Wasp Junior, and the Twin Wasp. For a brief period of time they tried to market the Twin Hornet and were working behind the scenes on the R-2000, the R-2800 and several liquid cooled projects. And they still had trouble with the 2 stage supercharger on the R-1830. An extra 10% of displacement probably wouldn't have turned things around much going for the R-2000. Plwase remember that 14 R-2800 sized cylinders work out to 2180 cu in and also that the later high powered R-2800s had little more in commen with the 2000hp versions than the bore and stroke. Forged heads instead of cast, cylinder barrels with Aluminum fin muffs on them instead of machined steel fins, different crankcases, crankshafts, pistons and so on. Without a total redsign of the R-1830 (and different manufacturing techniques) the R-1830 was not going to reach the output of the later R-2800s per cubic inch.

Click to expand...

Did I say no more Wright R-1820s? Anyway, I also said fighter production and meant it. Someone needed the money to build a two stage supercharger, denying one and feeding the other might be the ticket.

While you can cetainly put a P-40E style wing on a P-36 style fuselage and put in armour and self sealing tanks, the two stage supercharged R-1830 might have been just a bit harder. The weight might not have been a big problem but the volume needed by the intercooler might have been just little more difficult.

THe demonstrated performance of the R-1830 engine, while better than the Allison engines, wasn't so dramaticly better that the draggier radial engine vesion would have turned into a super fighter. the Two stage engine offered 1000hp at 19,000ft at "military rating". If somebody has any better information please let me know.

The P&W sytem of two stage superchargering was different than the Merlins. The P&W system used an engine driven supercharger with one gear ratio. the auxilary stage was not driven at sea level or for takeoff so the engine operated as a single stage engine until the hight of about 8-9,000 ft was reached at which point the auxilary supercharger was clutched in. This boosted the poer but as the plane climbd the power fell off untill the plane reached aboiut 16,000-17,000 at which point the auxilary supercharger shifted to high gear and power peaked at 19,000ft. The intercooler was between the auxialry stage and the engine supercharger and so did nothing to cool the intake charge after it left the engine supercharger, The intercooler was an air to air unit but I have no idea how good it was.
Note that as far as I can tell this is just about the same system used on the R-2800s in the F4U, the Hellcat and the P-61 A B models.

If the P-51 had flown as a Merlin powered plane from the start it would have first shown up in the Summer of 1942 ( using the 2 speed but not 2 stage engines from the P-40F) which would mean well over 600 Allison engined versions not being produced and probably a several month delay in getting the production ramped up for the Merlin version. P-51B is still going to have to wait for the 2 stage Merlin to be developed and put into mass production.
It might have ment no Mustang at all. With no Merlins ( of any supercharger type ) available from US sources in 1940 the British might never have signed the contract to develop the Mustang.

Click to expand...

I'm talking about a plane at least as much a new plane as the P-40 was with a radial engine instead of an inline. I'm not talking about bolting new models of R-1830 onto the old P-36 airframe. I would want one capable of getting the R-2000 when available.

First the R1830 has more frontal area = more drag
Allison should have gone on their own dime and continue both the turbosuper-charger and multi-stage superchargers the P-39 was estimated to be capable of 375mph at 20000 ft with the turbo (fully armed and armored)

If allison had done this R&D the perhaps the P-51A could have had much better performance on a V-1710

Did I say no more Wright R-1820s? Anyway, I also said fighter production and meant it. Someone needed the money to build a two stage supercharger, denying one and feeding the other might be the ticket.

Click to expand...

No you didn't but by leaving the R-1820 out of the decision you leave them in the market place. Wright only has to compeate with the engine maker YOU leave in the market.

I am not so sure money was the real problem. Knowledge and experience was probably a much bigger problem when it cam e to superchargers at the time and just throwing money at doesn't solve that problem.

I'm talking about a plane at least as much a new plane as the P-40 was with a radial engine instead of an inline. I'm not talking about bolting new models of R-1830 onto the old P-36 airframe. I would want one capable of getting the R-2000 when available.

Click to expand...

Just how much of a new plane was the P40?
Or which P-40 are we talking about?

And just what makes you think the R-2000 was going to be a world beater?

Nice engine yes but in the early versions it was good for 1350HP. Not a huge improvement over some of the existing engines. It was also later in timing than the R-2800.

First the R1830 has more frontal area = more drag
Allison should have gone on their own dime and continue both the turbosuper-charger and multi-stage superchargers the P-39 was estimated to be capable of 375mph at 20000 ft with the turbo (fully armed and armored)

Click to expand...

Allison wasn't going to do much more than they were doing "on their own dime". Allison was actually a rather small division of General Motors that made the majority of their money manufacturing engine bearings. In the !938 time frame they had according to one account , 25 employees in the engineering section including the blue print boys. By the end of WW II Allison had 1000 peaple working in the engineering section.
Allison had also only sold a few dozen engines before they got the contract for the P-40 engines in 1939. Without that contract there was a very real possiabilty that GM would have shut them down as an engine maker. GM having already pumped hundreds of thousand of dollars into Allison by that time.

General Electric was responsable all the turbochargers used on American aircraft from WW I to after WW II.
Setting up a rival operation wasn't going to be cheap or quick. Somebody else tried and it went nowhere.

In fact the pool of knowledgeable peaple in the US on superchargers was rather small at the time. Curtiss, Packard, P&W and Wright all having relied on GE for compressor designs in the 1920s and into the thirties. From the mid thirities on the companies still making aircraft engines became dissatified with the GE designs (which really weren't that good) and started designing their own. What wasn't known at the time was that some of the formulas in the text books were faulty. So you either need some genius (like Hooker in England) to discover the formulas are wrong or you need a lot of expensive experiments where the results don't corospond to the therory (somebody would have caught on if Hooker hadn't) to get you on the right track.

You still can't cheat time and space (unless you are Dr. Who). The P-39 was simply too small to house an effective intercooler no matter how good your supercharger design. Even the stretched P-63 didn't have room for the intercooler.